Errors reading with a HP 82153A Barcode Optical Wand



#24

Hello! I've tried to read with a wand, any rows printed from a PDF of the HP 41 math book, taken from this MoHPC, but I got a "reading error" or something which sounds like that. I've tried to print with a better quality mode but I'm pretty sure that the problem was in the definition of the the scan. If I compare for example the original of one of this book (the wand manual, for example)with a scanned copy of this Museum from which I get errors I don't see the difference....
Then I thought: "maybe the size of the scanned row is not the same", but I think that if bars are in scale there are no difference in reading....
May somebody help me to understand where could be the problem?

Many thanks for the help and for the patience in reading me.


Edited: 4 Apr 2012, 10:43 a.m.


#25

I have had trouble reading from a copy that was scanned and later printed out. I'll be able to read some rows and others will read after multiple attempts but I have never had much luck reading in a full program without errors. Have you been able to read in any rows?

The other thing I have tried with which I have had some success is to enlarge the original document when I print it out. That helps sometimes.

Cheers,

-Marwan


#26

Actually I can say the the wand works with original printed rows, but not with any of the prescanned/printed, altough theese are larger than the original ones! The problem is that I have no original books and original barcoded programs, except the wand user guide.... I thought to be able to read from PDF documents, but I can't!!

Edited: 4 Apr 2012, 11:11 a.m.


#27

Yes. I have had exactly the same problems. My question was, though, can you read *any* of the scanned/printed rows? Remember that you don't have to read them in order so try to read some of the other rows in the printout (other than the first row). Also, try *REALLY* enlarging a couple of rows (I took the scanned copies and printed them out in landscape so as to make them REALLY big.

With the document I tried to scan I think that the original scan was of such poor quality that there was a lot of bleeding along the edges of the bars and this cause a problem for the wand.

Cheers,

-Marwan


#28

If there is a lot of "bleeding" (by which I assume you mean variable gray scale in the transition from black to white and vice-versa), you might try to extract the scanned figure, if it is an embedded graphic in the pdf. You probably need real acrobat to do this, though. I don't know if Adobe reader can do it.

Once you have the graphic, put it in some graphic manipulation program (Photoshop Elements is fine, or you probably have similar capabilities in some program which came with your digital camera) and adjust the contrast (make it more contrast-y) or vary the clipping level between black and white.


#29

It means, if I've understood, that I must edit the PDF in way to obtain a "readable" image... (a sort of post editing, reverese engineering...)
I'm not so skilled in this matter (I mean professionaly) but but I've enjoyed theese applications for a home use. I should try, maybe after several attempts, I can succeed, thank-you

Edited: 4 Apr 2012, 12:36 p.m.

#30

That is exactly what I meant by bleeding. Good idea. I hadn't tried that. I ended up entering the program I was having trouble with and then saving to disk.

Cheers,

-Marwan

#31

Hi Marwan I can't read any of the scanned rows: I tried changing the speeed, the order (from left to right and viceversa), from the last to the first, there's no way. I've not yet tried to magnify them "REALLY", i'll dot it, keeping you informed, thank-you

EDIT: even after the reading of the double sized rows I get the same response: "CHECKSUM ERR"


Edited: 4 Apr 2012, 2:12 p.m.

#32

When I had a Wand, I gave up on trying to read scanned-in bar codes. It was much easier to just take the original program listing and use the utility to convert to a bar code file I could print out. Bar codes created this way always read with the wand.

Bill


#33

Hi Bill, I was oriented to try this solution. I knew of this utility but I don't remember where to find it, may you tell me, please?


#34

Hi.

There is a DOS-based utility (have it here somewhere...) that does not run under Windows. Actually it freezes the computer (and makes the printer to behave crazy) if we load it and try to print under DOS. I had it installed under Windows 97 and when printing I had to restart the computer under DOS and use print command to print the resulting document.

Cheers.

Luiz (Brazil)

#35

There's a couple of methods:

HP-41UC, which is dos based.

HP-41UC

The other is an Excel Sheet, that was done by Dan McDonald:

Excel Bar Code

Bill


#36

Thank-you, the ones I meant, thanks again

#37

Quote:
There's a couple of methods:

HP-41UC, which is dos based.

HP-41UC

The other is an Excel Sheet, that was done by Dan McDonald:

Excel Bar Code

Bill


Wow, Bill... that was a long time ago.

Once I saw/used Leo Duran's HP-41UC, I completely gave up on anything that I could create myself, because that program is so totally awesome.

Sad to say, it (HP41UC) won't run on my current default machine which is blessed with Windows 7, but I have other "modern" hardware which is capable of making it work.

If somebody is interested in making their own barcode for the HP41, including printing it for scanning, I 100% completely recommend the HP41UC program, even if you have to keep around some DOS-capable extra hardware to make it work.

Happy calculating, and happy barcoding.......

Dan M.


#38

Hi there,

It may be old, but it was (still is) very useful.

I'm currently using Leo's converter to handle .wnd files, and your barcode trutype font to create a printable document (not Postcrip) as a part of the development of the Wand emulation for the USB-41 adapter. (No, it is not ready yet...)

Thank you for giving us such nice tools. :-)

Cheers from the Canary Islands.

Diego.

#39

There's another tool: NutStudio tools goes RPN (HP-41)

Quote:
2. A barcode generator that accepts RPN programs in the same format as rpncomp that generates Postscript output that can be read by the 82153A Wand.

Best regards

Thomas


#40

There's also a simple web-based barcode generator at
http://rwiker.github.com/hp41barcode/ . Works for most reasonable browsers, plus IE9 (and possibly also IE8)...


#41

Hi, Raymond.

I inspected the source code (HTML) of the resulting page and surprisingly found a sequence of codes (rectangles) like this one:

<rect fill="black" height="30" width="1.575" y="44" x="20"></rect>
I mean, the bars are actually drawn as rectangles with height="30" and width="1.575" for 'zero' or width="3.3249999999999997" for 'one'. y="44" is the relative location of ROW 1, being y="86" for ROW 2, y="128" for ROW 3 and so. The x="20" is the horizontal position of the bar, and it goes higher for each new bar, depending on the previous one being a '0' or a '1'.

It has probably taken some time to get to this format, but once the bars are generated this way, I guess the printout will be clean and free of bleeding (shaded areas between spaces and bars).

I liked it very much!

Thanks.

Luiz (Brazil)

Edited: 5 Apr 2012, 6:02 p.m.

#42

Hi.

As we all (many of us...) know, the HP41 system itself comes from a time were memory was kind of a luxury. Although ROM was not that much expensive as RAM, addressing was also tricky, and because the HP41 uses a serial addressing mode, large amount of memory would also take larger amount of time to read/write (sorry if I am teaching priests how to pray...).

Card readers, tape drivers and the wand as well use a, say, heterogeneous, 'variable' media as a place to store information. Although reliable under certain considerations, in all three cases there is no way to make sure the system will provide a constant read/write speed while either storing/retrieving information. Neither the card reader nor the tape driver use step motors, so small yet acceptable speed variations while reading data should be corrected by software, and error-correcting software tends to grow in size faster than they grow in recovery capabilities. Our HP41 system is not big enough for providing larger data recovery routines, so the best ratio between efficiency and system use is supposed to be achieved. And we all know that storing a program in magnetic card or in magnetic tape does not ensure success in any future retrieval.

Storing data coded in bars gives us a far more stable representation WHEN we have a high-quality printing system. I have tested scanned images from bar codes and I always use 400dpi or more when scanning original printout. After that, I reduce colors to two (B&W) when printing so there is no 'in between' gray, shaded area. It is either space or black printing. The wand SW has a limited error correcting algorithm for reading bars mostly based on speed variations, i.e., because we cannot ensure our arm provides constant speed while reading, the 'size' of the bars is not constant (time measured when reading spaces and printed bars), and there are two types of bars. The small error-correcting portion of the reading routine constantly adjusts input data so the best ratio possible is achieved, so if there are both variations in speed while reading AND variations in the size of the printed bars, I guess the error correcting routines will fail.

I have a Brazilian magazine form the 80's with very interesting information about the HP wand system. I'll locate it and find the reference to the original English article and post about it later.

Cheers.


#43

Thank-you Luiz, I'm just one of the people in this forum who has more "to learn" than "to teach", so I really appreciate your explanation.


#44

Ciao, Aurelio.

Thanks you for your comments and considerate words, I appreciate.

I found the magazine and the referenced article; it could not be another one but the Hewlett-Packard Journal, January 1981. The magazine is the Elektor Electronics, Brazilian Edition (first print), issues #4 and #5, respectively October and November, 1986. Edition #5 is particularly interesting because it dedicates nothing but eight full pages to the HP wand reading details, mainly the one used in the HP41.

Cheers.

Luiz (Brazil)


#45

One item about use of the wand that struck me was that the faster a scan was done, the more reliable the results tended to be. Instead of the natural tendency to scan slowly to make sure the data gets into the '41, I never could enter a scan *too* quickly. And the inertia of a fast scan reduces the bar-to-bar timing changes due to speed variation.

Richard Nelson showed me this back in the day and it served me well. You may want to give it a try and see if it helps.

Considering that we made successful scans of printed barcodes done on Epson dot-matrix impact printers, HP 7470A pen plotters and all sorts of other devices with far worse resolution than anything we all use today, I believe the wand is up to the job.

#46

There is probably nothing the matter with your wand. I have never had a lot of success with wanding any of those PDF scans--too much artifact.

I have had much better luck typing up the program listing as a text file or cutting and pasting it if I am lucky enough to find it (there are many such listings in this site's software library), and creating and printing my own barcode on a cheap laser printer after converting the text file to barcode with Leo Duran's superb and very easy to use DOS utility, hp41uc.exe.

Don't drive yourself too crazy.

Les


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